System access method and apparatus of a narrowband terminal in a wireless communication system supporting wideband and narrowband terminals

ABSTRACT

Apparatuses (including base stations and terminals), systems, and methods for supporting both wideband and narrowband communications are described. In one aspect, a base station supporting first type terminals operating on a first bandwidth and second type terminals operating on a second bandwidth is described, having an information formatter, a transceiver, and a controller. The information formatter generates a Low-end Master Information Block (L-MIB) and a Low-end System Information Block (L-SIB), which are transmitted by the transceiver to first type and second type terminals. The L-MIB includes control information on an L-subframe configuration for supporting a second type terminal and a sub-band configuration of the L-subframe, while the L-SIB includes information on downlink reception and uplink transmission of the second type terminal. When the base station receives a Random Access Channel (RACH) preamble request from one of the terminals, the base station performs the random access procedure.

PRIORITY

This application is a continuation of, and claims priority under 35U.S.C. §120 to, U.S. patent application Ser. No. 13/625,468 filed onSep. 24, 2012 and issuing on May 12, 2015 as U.S. Pat. No. 9,031,019,which in turn claimed priority under 35 U.S.C. §119(a) to Korean patentapplication Ser. No. 10-2011-0096206, which was filed in the KoreanIntellectual Property Office on Sep. 23, 2011, the entire disclosures ofeach of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a cellular radiocommunication system and, in particular, to a system access method of anarrowband terminal in a cellular radio communication system supportingboth wideband and narrowband terminals.

2. Description of the Related Art

Long Term Evolution (LTE) utilizes Orthogonal Frequency DivisionMultiplexing (OFDM) in a downlink and Single Carrier Frequency DivisionMultiple Access (SC-FDMA) in an uplink. Such a multiple access techniqueis characterized in that time-frequency resources carrying data orcontrol information are arranged orthogonally to discriminate amongper-user data and/or control information.

FIG. 1 illustrates a basic structure of time-frequency grid of radioresource for transmitting data and control channels in a downlink of aconventional LTE system.

In FIG. 1, the horizontal axis denotes time, and the vertical axisdenotes frequency. An OFDM symbol is the smallest transmission unit onthe time axis, a slot 106 includes N_(sym) OFDM symbols 102, and asubframe 105 includes two slots. A slot is 0.5 ms, and a subframe is 1.0ms. A subcarrier is the smallest transmission unit in the frequencydomain, and the entire system transmission band includes N_(BW)subcarriers 104.

In the time-frequency grid, a Resource Element (RE) 112 is the basicunit indicated by an OFDM symbol index and a subcarrier index. TheResource Block (RB) or Physical Resource Block (PHB) 108 includes theN_(symb) consecutive OFDM symbols in the time domain 102 and the N_(RB)consecutive subcarriers in the frequency domain 110. Accordingly, an RB108 includes N_(symb)×N_(RB) REs. An RB is the smallest unit that can bescheduled for transmission. In an LTE system, N_(symb)=7 and N_(RB)=12,and N_(BW) and N_(RB) is in proportion to the system bandwidth.

The control information is transmitted in N OFDM symbols at thebeginning of the subframe. Typically, N={1, 2, 3}. Accordingly, theamount of control information carried in a current subframe depends onthe value of N. The control information includes an indicator thatindicates the number of OFDM symbols carrying the control information,uplink and downlink scheduling information, Hybrid Automatic RepeatreQuest (HARQ) Acknowledgement (ACK)/Negative ACK (NACK) signal,Multiple Input Multiple Output (MIMO)-related control information, etc.

The LTE system utilizes HARQ for retransmitting data that fails decodingin the physical layer. HARQ is a technique for ensuring reliability ofdata transmission in such a way that a receiver transmits a NACK to atransmitter to request a retransmission of the data that has faileddecoding in the physical layer. The receiver combines the retransmitteddata with the previously transmitted data to increase the data receptionperformance. If data is decoded successfully, the receiver transmits anACK to the transmitter such that the transmitter can transmit next data.

In a cellular radio communication system, scalable bandwidth is asignificant feature for providing various types of data services. LTEsupports scalable bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz. Thesebandwidths correspond to 6, 15, 25, 50, 75, and 100 RBs, respectively.The mobile carriers use one of the available bandwidths to providedservices. However, it is then necessary for the LTE system having aspecific system bandwidth to support the terminals with differentbandwidth capabilities.

For example, an LTE system having a 10 MHz system bandwidth cannotsimultaneously support a 10 MHz terminal and a 1.4 MHz terminal,Basically, the terminal supporting the bandwidth that is narrower thanthe system bandwidth cannot receive a downlink control channel that istransmitted across the entire system bandwidth in the LTE system.

Also, terminals supporting different bandwidths may interfere with eachother.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to solve the aboveproblems and to provide at least the advantages described below.

Accordingly, an aspect of the present invention is to provide a systemaccess method that is capable of supporting both wideband and narrowbandterminals in a wireless communication system.

In accordance with an aspect of the present invention, a base station ina wireless communication system supporting first type terminalsoperating on a first bandwidth and second type terminals operating on asecond bandwidth is provided, the base station including an informationformatter; a transceiver; and a controller configured to control theinformation formatter to generate a Low-end Master Information Block(L-MIB) and a Low-end System Information Block (L-SIB), control thetransceiver to transmit the generated L-MIB and L-SIB, and perform arandom access procedure, when a Random Access Channel (RACH) preamblerequest is received from one of the first type terminals and the secondtype terminals, wherein the L-MIB includes control information on anL-subframe configuration for supporting a second type terminal and asub-band configuration of the L-subframe, and wherein the L-SIB includesinformation on downlink reception and uplink transmission of the secondtype terminal.

In accordance with another aspect of the present invention, a terminalin a wireless communication system supporting first type terminalsoperating on a first bandwidth and second type terminals operating on asecond bandwidth is provided, the terminal including a transceiver; anda controller configured to control the transceiver to receive aSynchronization CHannel (SCH), a Low-end Master Information Block(L-MIB), and a Low-end System Information Block (L-SIB) and to transmita Random Access Channel (RACH) preamble to the base station based on thereceived L-MIB and the received L-SIB, wherein the received L-MIBincludes control information on an L-subframe configuration forsupporting a second type terminal and a sub-band configuration of theL-subframe, and the L-SIB includes information on downlink reception anduplink transmission of the second type terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a basic structure of a time-frequency grid of a radioresource for transmitting data and control channels in a downlink of aconventional LTE system;

FIG. 2 illustrates a method of multiplexing a Normal-User Equipment(N-UE) and a Low-end UE (L-UE) in an LTE Frequency Division Duplexing(FDD) system according to an embodiment of the present invention;

FIG. 3 illustrates a method of multiplexing an N-UE and an L-UE in anLTE Time Division Duplexing (TDD) system according to an embodiment ofthe present invention;

FIG. 4 illustrates a time-frequency resource in respective N-subframeand L-subframe for multiplexing an N-UE and an L-UE in an LTE systemaccording to an embodiment of the present invention;

FIG. 5 illustrates a sub-band having an L-UE-specific Physical DownlinkControl Channel (L-PDCCH) configured in a Frequency DivisionMultiplexing (FDM) mode in a subframe having a control region of twoOFDM symbols at its beginning, according to an embodiment of the presentinvention;

FIG. 6 illustrates a sub-band having an L-PDCCH configured in a TimeDivision Multiplexing (TDM) mode in a subframe having a control regionof two OFDM symbols at its beginning, according to an embodiment of thepresent invention;

FIG. 7 illustrates a sub-band having an L-PDCCH configured in an FDM/TDMmode in a subframe having a control region of two OFDM symbols at itsbeginning, according to an embodiment of the present invention;

FIG. 8 is a flowchart illustrating a UE procedure for receiving L-MIBand L-SIB and performing a random access procedure according to anembodiment of the present invention;

FIG. 9 illustrates a detailed time-frequency resource configuration ofan uplink in an N-subframe and an associated L-subframe in an LTE systemsupporting N-UE and L-UE multiplexing, according to an embodiment of thepresent invention;

FIG. 10 illustrates a sub-band configured for transmitting a Low-endSounding Reference Signal (L-SRS) of an L-UE in an LTE system accordingto an embodiment of the present invention;

FIG. 11 illustrates a sub-band configured for use by an L-UE in anassociated L-subframe in an LTE system according to an embodiment of thepresent invention;

FIG. 12 is a block diagram illustrating an evolved Node B (eNB)according to an embodiment of the present invention; and

FIG. 13 is a block diagram illustrating an L-UE according to anembodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention are described in detailbelow with reference to the accompanying drawings. However, detaileddescriptions of well-known functions and structures incorporated hereinmay be omitted to avoid obscuring the subject matter of the presentinvention.

Terms used herein are defined by taking functions of the presentinvention into account and can be changed according to the practice orintention of users or operators. Therefore, definition of the termsshould be made according to overall disclosures set forth herein.

In the following description, a base station, i.e., a host, can be, forexample, at least one of a Node B, an eNB, a radio access unit, a basestation controller, or a specific node on the network. The terminal canbe, for example, a UE, a Mobile Station (MS), a cellular phone, asmartphone, a computer, or a multimedia system equipped withcommunication function.

Herein, the term “DownLink (DL)” denotes a transmission path of a radiosignal from a base station to a terminal, and the term “UpLink (UL)”denotes a transmission of a radio signal from a terminal to a basestation.

Although embodiments of the present invention will be described belowwith reference to LTE and LTE-Advanced (LTE-A) systems, it will beunderstood by those skilled in the art that the present invention isalso applicable to other communication systems having similar technicalbackgrounds and channel formats, with slight modifications, withoutdeparting from the spirit and scope of the present invention.

For simplicity, a legacy wideband LTE terminal supporting a systembandwidth a mobile communication system is referred to herein as a“Normal UE (N-UE)”. Also, the term “first type terminal supporting firsttype bandwidth” is interchangeably used with N-UE, under an assumptionthat the first type bandwidth is wider than a second type bandwidth, aswill be described later.

An LTE terminal supporting a narrower bandwidth than a system bandwidthis referred to as a “Low-end UE (L-UE)”. Also, the term “second typeterminal supporting the second type bandwidth” is interchangeably usedwith L-UE, under the assumption that the second type bandwidth isnarrower than the first type bandwidth.

For example, the L-UE can be a low cost or low-end terminal supportinglow data rate service such as voice communication and Machine TypeCommunication (MTC) or Machine-to-Machine (M2M) service, as compared toN-UE.

In accordance with an embodiment of the present invention, a physicalchannel and control information of a legacy LTE system are reused asmuch as possible to support the L-UE while minimizing system designcomplexity. However, there are still problems to be addressed forsimultaneously supporting both the N-UE and L-UE in the LTE system. Forexample, when the N-UE supporting wideband and the L-UE supportingnarrowband coexist in the LTE system, the L-UE cannot receive a PDCCHdesigned for the legacy N-UE to receive across the entire system band.If an L-PDCCH is defined in a time-frequency resource for carrying thelegacy PDCCH, the legacy N-UE has to know the location of the resourcemapped to the L-PDCCH to receive the PDCCH addressed to the N-UE. Inorder to accomplish this, in accordance with an embodiment of thepresent invention, a method for time-division multiplexing the controlchannels addressed to the N-UE and L-UE is provided.

FIG. 2 illustrates a method of multiplexing an N-UE and an L-UE in anLTE FDD system according to an embodiment of the present invention, andFIG. 3 illustrates a method of multiplexing an N-UE and an L-UE in anLTE TDD system according to an embodiment of the present invention.

For an LTE downlink, a location of a subframe carrying an essentialphysical channel and Synchronization CHannel (SCH) as controlinformation, a Physical Broadcast CHannel (PBCH), a paging message, anda System Information Block (SIB) is fixed.

According to the LTE FDD specification, the SCH is carried in subframe#0 and subframe #5, the PBCH is carried in subframe #0, the pagingmessage is carried in subframe #0, subframe #4, subframe #5, andsubframe #9, and the SIB is carried in subframe #5. These subframes arereferred to as Normal-subframes (N-subframes).

The SCH includes a Primary Synchronization Sequence (PSS) and aSecondary Synchronization Sequence (SSS) as downlink physical channelsfor the UE to acquire radio frame timing synchronization and a cellIDentifier (ID). The SCH is mapped to 62 REs in the center frequency ofthe LTE system bandwidth.

The PBCH provides a Master Information Block (MIB) carrying coreinformation for a UE to access a system, such as DL system bandwidth,Physical HARQ Indicator CHannel (PHICH) resource information, and aSystem Frame Number (SFN). The PBCH is mapped to 72 REs in the centerfrequency of the LTE system bandwidth in the frequency domain.

The paging message is transmitted by an eNB in the downlink to notifythe UE in an idle mode of an incoming call or a change of an SIB of thecorresponding cell. The SIB is the control information required for theUE to access the system in addition to the MIB and includescell-specific radio resource configuration information. The SIB istransmitted to the UE through Physical Downlink Shared Channel (PDSCH)as downlink physical data channel.

As illustrated in FIG. 2, subframe #0, subframe #4, subframe #5, andsubframe #9 are N-subframes among the 10 total subframes of a radioframe 200, according to the FDD LTE standard. The L-UE according to anembodiment of the present invention receives the SCH and PBCH at leastamong the physical channels and control information in order to acquireradio frame timing synchronization, a cell ID, and an MIB.

The eNB transmits a downlink control channel or a data channel forsupporting the L-UE in subframes other than N-subframes in a radioframe. These subframes are referred to as potential L-subframes, and theL-subframe, which actually carries the control channel or data channelfor supporting the L-UE is referred to as an L-subframe 230. The term“L-subframe” indicates the subframe designated for the second typeterminal supporting a bandwidth narrower than the system bandwidth, butis not restricted to meaning a subframe for dedicated use by the secondtype terminal. That is, the L-subframe can be used for control or datachannel transmission for the first type terminal too.

According to the FDD LTE standard, subframe #1, subframe #2, subframe#3, subframe #6, subframe #7, and subframe #8 are the potentialL-subframes.

In FIG. 2, subframe #2 is configured as L-subframe. Further, althoughFIG. 2 is directed to a case where only one subframe is configured as anL-subframe, it is possible for one or more subframes to be configured asan L-subframe.

If the eNB transmits downlink data to the L-UE in subframe #2, the L-UEfeeds back a HARQ ACK/NACK corresponding to the received downlink data.The L-UE transmits the HARQ ACK/NACK to the eNB, after a predeterminedtime, in consideration of the reception signal processing time for thedownlink data.

In FIG. 2, the L-UE transmits the HARQ ACK/NACK to the eNB in subframe#6, assuming that the signal processing time is 4 subframes.

In accordance with an embodiment of the present invention, the subframeassociated with the L-subframe 230 in HARQ timing relationship isreferred to as an “associated L-subframe 240”. The eNB uses 1 to 3 OFDMsymbols at the beginning of the L-subframe 230 for transmitting controlsignal addressed to the N-UE and the rest for transmitting control ordata channel for supporting the L-UE.

Referring to FIG. 3, in the LTE TDD standard, the subframes of a radioframe are sorted into uplink and downlink subframes according to a TDDUL/DL configuration. Subframe #0, subframe #1, subframe #5, and subframe#6 are fixed as downlink subframes, regardless of the TDD UL/DLconfiguration, and subframe #2 is fixed as an uplink subframe. Among thedownlink signals, an SCH is transmitted in subframe #0, subframe #1,subframe #5, and subframe #6; a PBCH is transmitted in subframe #0, apaging message is transmitted in subframe #0, subframe #1, subframe #5,and subframe #6; and an SIB is transmitted in subframe #5.

Accordingly, for LTE TDD, subframe #0, subframe #1, subframe #5, andsubframe #6 of one radio frame 300 are N-subframes 310; and subframe #3,subframe #4, subframe #7, subframe #8, and subframe #9 are potentialL-subframes 320. Subframe #3, subframe #4, subframe #7, subframe #8, andsubframe #9 can be used as uplink or downlink subframes according to theTDD UL/DL configuration.

FIG. 4 illustrates a time-frequency resource in respective N-subframeand L-subframe for multiplexing an N-UE and an L-UE in an LTE systemaccording to an embodiment of the present invention.

Referring to FIG. 4, the system bandwidth is 5 MHz and includes 25 PRBs,i.e., PRB #0 to PRB #24. The N-UE is a broadband UE supporting abandwidth of 5 MHz, which is equal to the system bandwidth, and the L-UEis the narrowband UE supporting a bandwidth of 1.4 MHz, which isnarrower than the system bandwidth. The eNB divides the system bandwidthto secure one or more sub-bands for the L-UEs in the L-subframe.

In FIG. 4, three sub-bands, i.e., sub-band #1 402, sub-band #2 404, andsub-band #3 406, are used. Each sub-band has a bandwidth of 1.4 MHz andincludes 6 PRBs such that the L-UE can support the sub-band. The L-UEoperates in one of the sub-bands 402, 404, and 406. The sub-bands arespaced apart to minimize the interference to each other. Sub-band #1 402is spaced apart from an edge of the system band as much asf_(dl,offset,edge) 410 and from the sub-band #2 404 as much asf_(dl,offset,Inter) 412. Sub-band #3 406 is spaced apart from the otheredge of the system band as much as f_(dl,offset,edge) 416 and from thesub-band #2 404 as much as f_(dl,offset,Inter) 414. The offsets, i.e.,f_(dl,offset,edge) 410, f_(dl,offset,Inter) 412, f_(dl,offset,Inter)414, and f_(dl,offset,edge) 416, and the bandwidth of each sub-band aresignaled from the eNB to the UE or set to hardcoded values agreedbetween the eNB and the UE.

During the N-subframe 418, the L-UE stops receiving data or controlsignal from the eNB while the N-UE receives data or control signaltransmitted by the eNB. The eNB transmits the control signal addressedto the N-UE in N OFDM symbols 422 at the beginning of the N-subframe andtransmits the data signal addressed to the N-UE in the rest symbolsduration 424. The control signal includes the control informationindicating the value of N, the control information for schedulingdownlink or uplink data signal, and a HARQ ACK/NACK, and isdistributively transmitted across the entire system band.

The eNB transmits the control information for supporting the legacy N-UEin the N OFDM symbols duration 426 at the beginning of the L-subframe420. The control information includes the control information indicatingthe value of N, the control information for scheduling an uplink datasignal, and a HARQ ACK/NACK, and is distributively transmitted acrossthe entire system band. The L-UE does not receive the controlinformation or the data signal from the eNB during the N OFDM symbolsduration 426 at the beginning of the L-subframe 420.

The eNB transmits the control information or data for supporting theL-UE during the rest time duration of the sub-bands 428, 429, and 430,i.e., the time duration following the first N OFDM symbols region of theL-subframe. In this case, a certain L-UE operates in one of thesub-bands. For example, if the L-UE #1 operates on the sub-band #1 402,the eNB transmits the control information and data addressed to the L-UE#1 on the region 403 of the sub-band #1 402. If the L-UE #2 operates onthe sub-band #2 404, the eNB transmits the control information and dataaddressed to the L-UE #2 on the region 429 of the sub-band #2 404.

The eNB uses the resource corresponding to the region 432, 434, 436, and438, other than the sub-band #1 402, sub-band #2 404, and sub-band #3406 for data transmission to the legacy N-UE. Further, the eNBmultiplexes the data addressed to the legacy N-UE and the data addressedto the L-UE into the resource regions 428, 429, and 430.

Table 1 shows the sub-band sizes and number of sub-bands available forsupporting L-UE per LTE system bandwidth. For example, the systembandwidth of 5 MHz can be divided to configure 1, 2, or 3 sub-bands of1.4 MHz or 1 sub-band of 3 MHz. At this time, the sum of the bandwidthsof the sub-bands cannot exceed the system bandwidth of the LTE system.

TABLE 1 System bandwidth Combination of subbands (a × b; [MHz] a:subband bandwidth [MHz], b: number of subbands) 1.4 — 3 1.4 × 1, 1.4 × 25 1.4 × 1, 1.4 × 2, 1.4 × 3 3 × 1 10 1.4 × 1, 1.4 × 2, 1.4 × 3, 1.4 × 4,1.4 × 5, 1.4 × 6, 1.4 × 7 3 × 1, 3 × 2, 3 × 3 5 × 1, 5 × 2 15 1.4 × 1,1.4 × 2, 1.4 × 3, 1.4 × 4, 1.4 × 5, 1.4 × 6, 1.4 × 7, 1.4 × 8, 1.4 × 9,1.4 × 10 3 × 1, 3 × 2, 3 × 3, 3 × 4, 3 × 5 5 × 1, 5 × 2, 5 × 3 20 1.4 ×1, 1.4 × 2, 1.4 × 3, 1.4 × 4, 1.4 × 5, 1.4 × 6, 1.4 × 7, 1.4 × 8, 1.4 ×9, 1.4 × 10, 1.4 × 11, 1.4 × 12, 1.4 × 13, 1.4 × 14 3 × 1, 3 × 2, 3 × 3,3 × 4, 3 × 5, 3 × 6 5 × 1, 5 × 2, 5 × 3, 5 × 4

The method for configuring the control channel for supporting L-UE inthe sub-band for the time duration of L-subframe can be implemented invarious ways, e.g., FDM, TDM, or FDM/TDM. The control channel includesan L-PDCCH for scheduling the data for an L-UE and a Low-end PhysicalHARQ Indicator Channel (L-PHICH) for feedback of HARQ ACK/NACKcorresponding to the uplink data of the L-UE.

FIG. 5 illustrates a sub-band having an L-PDCCH configured in an FDMmode in a subframe having a control region of two OFDM symbols at itsbeginning, according to an embodiment of the present invention.

Referring to FIG. 5, the sub-band 516 includes 6 PRBs 522, and thecontrol channel 518 includes a PDCCH and a PHICH for the N-UE.

The L-PDCCH 520 is mapped to a specific PRB 626 among the 6 PRBsaccording to the eNB's decision, in order to be transmitted over thetime duration of the L-subframe 510, with the exception of the durationof the first two OFDM symbols. The L-PDCCH 520 provides the downlinkscheduling control information corresponding to the Low-end PhysicalDownlink Shared CHannel (L-PDSCH) 522, which is mapped to the PRB 528 onthe same sub-band in the same subframe, with the exception of theduration of its first two OFDM symbols. The eNB determines the PRBs towhich the L-PDCCH and the L-PDSCH are mapped among the PRBs of thesub-band based on the control information fed back by the L-UE. TheL-PDCCH and L-PDSCH are mapped to one or more PRBs. Typically, the eNBselects the PRB having the best channel condition. The L-PDCCHs fordifferent L-UEs are multiplexed in unit of PRB in the frequency domain(FDM).

The L-PHICH 524 is mapped to the OFDM symbols following the one carryingthe PDCCH or PHICH 518 for the N-UE as distributed in the time domain.Specifically, in FIG. 5, the L-PHICH is mapped to the OFDM symbol #2 asdistributed on a part of three PRBs. The number and location of the OFDMsymbols to which the L-PHICH is mapped and the detailed mappingpositions in the frequency domain may vary.

FIG. 6 illustrates a sub-band having an L-PDCCH configured in a TDM modein a subframe having a control region of two OFDM symbols at itsbeginning, according to an embodiment of the present invention.

Referring to FIG. 6, the control channel 618 of a PDCCH and/or a PHICHfor an N-UE is mapped to two OFDM symbols at a beginning of anL-subframe 610, and the L-PDCCH and L-PHICH for an L-UE are mapped tothe OFDM symbol #2, symbol #3, and symbol #4. The L-PDCCH 620 isdistributively transmitted across the entire bandwidth of sub-band, andthe L-PHICH 624 is segmented into small units in order to be distributedin the frequency and time domains. The L-PDCCHs for the L-UEs areinterleaved and multiplexed onto the region of the OFDM symbol #2,symbol #3, and symbol #4 in the sub-band without being overlapped.

The time duration for transmitting the L-PDCCH and L-PHICH can bedetermined based on a semi-static value signaled by the eNB throughhigher layer signaling or a value changing dynamically at every subframethrough physical layer signaling. The L-PDSCH 622 is mapped to thefrequency region indicated by the L-PDCCH after the time durationcarrying the L-PDCCH on the same sub-band in the same subframe.

FIG. 7 illustrates a sub-band having an L-PDCCH configured in an FDM/TDMmode in a subframe having a control region of two OFDM symbols at itsbeginning, according to an embodiment of the present invention.

Referring to FIG. 7, the sub-band 716 for L-UE includes 6 PRBs 730, andthe control channel 718 of PDCCH and/or PHICH for an N-UE is transmittedin two OFDM symbols at a beginning of an L-subframe 710. The L-PDCCH 720is mapped to a specific PRB 726 among the six PRBs according to theeNB's decision, in order to be transmitted for the time duration of slot#0 712 of the L-subframe, with the exception of the 2 OFDM symbols ofcontrol region.

The L-PDSCH 724, which is scheduled by the L-PDCCH 720, is mapped to thesame frequency region as the L-PDCCH 720 for the time duration of slot#1 714. Further, the L-PDCCH 720 can be configured for scheduling theL-PDSCH 722 mapped to other PRB 728. At this time, the L-PDSCH 722 ismapped to be transmitted for the entire duration of the L-subframe 710,with the exception of the control region carrying the PDCCH and/or thePHICH.

The L-PDCCHs for different L-UEs are multiplexed in units of a PRB inthe frequency domain (i.e., FDM) and multiplexed in units of a slot inthe time domain (i.e., TDM). The L-PHICH 725 is mapped to the symbolsfollowing the control region 718 of the PDCCH and/or PHICH asdistributed in the frequency domain. In FIG. 7, the L-PHICH is mapped tothe OFDM symbol #2 in the time domain and a part of each of threedifferent PRBs in the frequency domain.

The L-UE knows the control information on an L-subframe configurationand a sub-band configuration (hereinafter, referred to as an L-MIB) toreceive L-PDCCH, L-PHICH, and L-PDSCH. The L-MIB is included in a PBCHalong with the legacy MIB and broadcast by the eNB. The L-MIB istransmitted using the reserved bits of the legacy PBCH and follows therule of channel coding, modulation, and time-frequency resource mappingspecified in the LTE standard.

Accordingly, the N-UE can acquire MIB from the PBCH without error in theLTE system. The L-UE receives the PBCH to acquire both the legacy MIBand L-MIB.

The L-MIB includes the following control information:

Subframe set index: an indicator that indicates the L-subframe, which isone of the subframes, excluding the subframes carrying an SCH, a PBCH, apaging message, and an SIB. In an LTE FDD system, it is possible toindicate the L-subframe in the form of a bitmap for subframe #1,subframe #2, subframe #3, subframe #6, subframe #7, and subframe #8. Forexample, if subframe #1 and subframe #6 are configured as L-subframes,this can be indicated as [1, 0, 0, 1, 0, 0]. Here, bit positions of thebitmap correspond to the respective subframe #1, subframe #2, subframe#3, subframe #6, subframe #7, and subframe #8; and the bit correspondingto subframe configured as L-subframe is indicated is set to 1 and othersto 0.

-   -   L-PHICH resource information: indicates resource information of        an L-PHICH and includes a number of OFDM symbols to which the        L-PHICH is mapped or a resource amount in the time domain.    -   DL sub-band bandwidth configuration: indicates size of the        downlink sub-band for an L-UE supported in the LTE system, This        is set to a value less than the downlink system bandwidth of the        LTE system.    -   Search space: indicates a PRB to which an L-PDCCH can be mapped        in the downlink sub-band for an L-UE. The eNB selects at least        one PRB within the configured search space and maps the L-PDCCH        to be transmitted to each L-UE to the selected PRB.

The L-MIB may include some or all of the control information. When allof the control information is included in the L-MIB, the L-MIB isconfigured as shown below, although the relative position of eachcontrol information can be changed.

L-MIB={‘Subframe set index’, ‘L-PHICH resource information’, ‘DL subbandbandwidth configuration’, ‘Search space’}

When a part of the control information is included, the L-MIB can beconfigured as shown below. In this case, there is no control informationon the ‘search space’ such that the eNB is capable of transmittingL-PDCCH on a certain PRB in the ‘DL subband bandwidth configuration’.The control information on the ‘search space’ can be notified to the UEthrough a separate L-SIB.

L-MIB={‘Subframe set index’, ‘L-PHICH resource information’, ‘DL subbandbandwidth configuration’}

Alternatively, when a part of the control information is included, theL-MIB can be configured as shown below. In this case, the ‘Subframe setindex’ and ‘DL subband bandwidth configuration’ can be signaled to theUE through a separate L-SIB or set to predetermined hardcoded values.

L-MIB={‘L-PHICH resource information’, ‘Search space’}

The L-MIB may also be configured with only a ‘DL subband bandwidthconfiguration. In this case, the ‘Subframe set index’, ‘L-PHICH resourceinformation’, and ‘Search space’ can be signaled to the UE through aseparate L-SIB or set to predetermined hardcoded values.

L-MIB={'DL subband bandwidth configuration}

The L-MIB may also be configured with only ‘L-PHICH resource informationas shown below. In this case, the ‘Subframe set index’, ‘DL subbandbandwidth configuration’, and ‘Search space’ can be signaled to the UEthrough a separate L-SIB or set to predetermined hardcoded values.

L-MIB={‘L-PHICH resource information’}

The L-MIB may also be configured with only the ‘Subframe set index’ asshown below. In this case, ‘L-PHICH resource information’, ‘DL subbandbandwidth configuration’, and ‘Search space’ can be signaled to the UEthrough a separate L-SIB or set to predetermined hardcoded values.

L-MIB={‘Subframe set index’}

The L-MIB carries the information for receiving downlink controlchannels, i.e., an L-PDCCH, an L-PHICH, and an L-PDSCH, and theadditional control information for supporting an L-UE, i.e., thedownlink reception and the uplink transmission control information areconfigured in an L-SIB in order to be transmitted from the eNB to the UEthrough L-PDSCH.

The L-SIB includes the following information:

-   -   DL subband position: indicates the positing in the frequency        region of the downlink subband for an L-UE within the system        bandwidth of the LTE system and expressed by the first PRB index        of each subband or gap between subbands.    -   UL subband bandwidth configuration: indicates the size of uplink        subband for an L-UE within the uplink system bandwidth of the        LTE system. This parameter is set to a value less than the        uplink system bandwidth of the LTE system. When “UL subband        bandwidth configuration” is associated with “DL subband        bandwidth configuration,” such that the two parameters have the        same value or it is possible to acquire “UL subband bandwidth        configuration” from “DL subband bandwidth configuration”        included in the L-MIB according to a predetermined rule, the “UL        subband bandwidth configuration” signaling can be omitted.    -   UL subband position: indicates the position in the frequency        region of the uplink subband for an L-UE in the system bandwidth        of the LTE system and is expressed as the first PRB index of        each subband or the gap between subbands. When “UL subband        position” is associated with “DL subband position,” such that        the two parameters have the same value or it is possible to        acquire “UL subband position” from “DL subband position”        included in the L-SIB according to a predetermined rule, the “UL        subband position” signaling can be omitted.    -   PRACH configuration: is the RACH preamble sequence information        used by the L-UE to perform random access and includes the        information on the subband and subframe available for RACH        preamble transmission.    -   Physical Channel Configuration: includes the physical channel        control information for the L-UE to transmit or receive an        L-UE-specific Physical Uplink Control CHannel (L-PUCCH), an        L-UE-specific Physical Uplink Shared CHannel (L-PUSCH), L-PDSCH,        an L-UE-specific Channel Quality Indicator (L-CQI), L-SRS, etc.        The L-PUCCH is the physical channel for the L-UE to transmit        uplink HARQ ACK/NACK or the L-CQI and reuses the transmission        structure of PUCCH of the legacy LTE system. The L-PUSCH is the        physical channel for the L-UE to transmit uplink data and reuses        the transmission structure of the PUSCH of the legacy LTE        system. The L-PDSCH is the physical channel for the eNB to        transmit downlink data to the L-UE and reuses the transmission        structure of PDSCH of the legacy LTE system. The L-CQI is the        control information fed back from the L-UE to the eNB for the        purpose of link adaptation on the downlink physical channel and        includes channel condition information and MIMO-related control        information expressed by a Modulation and Coding Scheme (MCS).        In order to transmit the L-CQI, the L-UE should know the control        information, such as a transmission period of the L-CQI and a        report type. The L-SRS is the SRS transmitted for the eNB to        estimate the uplink channel condition. In order to transmit the        L-SRS, the L-UE should know the control information, such as a        frequency band and a subframe for the L-SRS transmission.

Prior to the UE operation, the eNB configures the detailed controlinformations included in the L-MIB and the L-SIB based on theinformation of the L-UEs to be supported in the LTE/LTE-A system, anumber of L-UEs, and available resource amount. The eNB completes theconfiguration about the detained control informations beforetransmitting a PBCH and an L-PDCCH/L-PDSCH and reflects theconfiguration in transmitting the PBCH and the L-PDCCH/L-PDSCH.

More specifically, the eNB generates an L-MIB including the controlinformation related to the L-subframe configuration and subbandconfiguration, and transmits the L-MIB to the UE through the PBCH. TheL-MIB may include at least one of a subframe configuration index,L-PHICH resource information, DL subband bandwidth configurationinformation, and a search space.

The eNB generates an L-SIB including additional control information forsupporting the L-UE, in addition to the L-MIB, and transmits the L-SIBto the UE through PDSCH scheduled by the L-PDCCH. The L-SIB may includeat least one of a DL subband position, UL subband bandwidthconfiguration information, UL subband bandwidth configurationinformation, a UL subband position, PRACH configuration information, andphysical channel configuration information.

Afterward, if an attach request is received from a UE, the eNB performsa random access procedure to accept the attach request of the UE.

FIG. 8 is a flowchart illustrating a UE procedure for receiving L-MIBand L-SIB and performing a random access procedure according to anembodiment of the present invention.

Referring to FIG. 8, the L-UE detects an SCH to access the system instep 800. Specifically, the L-UE acquires information, such as radioframe timing synchronization, a cell ID, and a Cyclic Prefix (CP) lengthfrom the SCH transmitted by an eNB. The SCH includes a PrimarySynchronization Sequence (PSS) and a Secondary Synchronization Sequence(SSS) and is mapped to subframe #0 and subframe #5 to be transmitted.The SCH is mapped to 62 REs in the center frequency of the LTE systemband in the frequency domain.

In step 810, the L-UE receives a PBCH including an L-MIB dedicated tothe L-UE, in addition to an MIB for an N-UE. The PBCH is mapped tosubframe #0 to be transmitted. The PBCH is mapped to 72 REs in thecenter frequency of the LTE system bandwidth. As described above, theL-MIB may include at least one of a DL subband position, UL subbandbandwidth configuration information, UL subband bandwidth configurationinformation, UL subband position, PRACH configuration information, andphysical channel configuration information.

In step 820, the L-UE acquires L-SIB from the L-PDSCH. The L-SIBincludes the control information for downlink reception and uplinktransmission. The L-UE checks the position of the time-frequencyresource to which the L-PDCCH is mapped based on the ‘search space’information provided in the L-MIB or according to a predetermined rule.The L-UE extracts the L-PDCCH to receive the L-PDSCH indicated by theL-PDCCH and acquires an L-SIB from the L-PDSCH.

As described above, the L-SIB may include at least one of a DL subbandposition, UL subband bandwidth configuration information, UL subbandbandwidth configuration information, UL subband position, PRACHconfiguration information, and physical channel configurationinformation. The L-PDSCH including the L-SIB and the L-PDCCH forscheduling the L-PDSCH are transmitted on a predetermined subband amongthe downlink subbands for L-UE supported by the LTE system and in apredetermined subframe.

In accordance with an embodiment of the present invention, the subbandpredetermined for transmitting the L-PDCCH includes the frequency regioncarrying the SCH and PBCH, such that the L-UE may receive an SCH, aPBCH, and an L-PDCCH, without changing a reception frequency band.

In step 830, the L-UE transmits the RACH preamble on a predetermineduplink subband (hereinafter, referred to as a first uplink subband).More specifically, the L-UE transmits the RACH preamble by referencing aRACH preamble sequence and subband, and subframe available for RACHpreamble transmission extracted from the PRACH configuration included inthe received L-SIB. Afterward, the L-UE receives a random accessresponse from the eNB in response to the RACH preamble and performsRACH-related process.

In accordance with an embodiment of the present invention, the L-UE iscapable of transmitting the RACH preamble in two ways, i.e., method 1and method 2.

Method 1 restricts the first uplink subband to the subband correspondingto the downlink subband in step 820. That is, the first uplink subbandis fixed as a certain subband in method 1. The one or more downlinksubbands for an L-UE in the LTE system bandwidth has relationship withone or more uplink subbands for L-UE.

In method 1, the L-UE communicates with the eNB through the fixedsubband during an initial random access procedure after receiving theSCH in order to minimize the transmission/reception complexity. If norandom access response is received from the eNB and thus the initialrandom access procedure fails, the UE transmits the RACH preamble on anuplink subband (hereinafter, referred to second uplink subband), whichis different from the first uplink subband, to resume the random accessprocedure. Consequently, the probability of a random access failure isreduced.

Unlike method 1, in method 2, the L-UE transmits the initial RACHpreamble without an uplink subband restriction. That is, the RACHpreamble is initially transmitted by the L-UE on an uplink subbandrandomly selected from among the uplink subbands included in the LTEsystem bandwidth. Method 2 reduces overload caused by a concentration ofthe RACH preamble transmissions on a specific subband.

In method 2, the L-UE acquires the control information related to theRACH on each uplink subband in an L-MIB and an L-SIB transmitted by theeNB in order to perform random access a certain uplink subband. The eNBconfigures the RACH-related control information of the respective uplinksubbands commonly or individually in adaptation to individual uplinksubbands.

When the random access procedure completes successfully in step 830, theL-UE transitions to a Radio Resource Control (RRC) connected(RRC_CONNECTED) state to transmit and receive data in a unicast manner.

FIG. 9 illustrates a detailed time-frequency resource configuration ofan uplink in an N-subframe and associated L-subframe in an LTE systemsupporting N-UE and L-UE multiplexing according to an embodiment of thepresent invention.

As described above, the associated L-subframe is in a HARQ timingrelationship with the downlink L-subframe and carries an uplink HARQACK/NACK and CQI feedback for an L-UE on an L-PUCCH and carries uplinkdata on an L-PUSCH. In the associated L-subframe, the PUCCH or PUSCH foran N-UE in the associated L-subframe can be transmitted without overlapwith the L-PUCCH or the L-PUSCH for the L-UE in the frequency domain.The N-subframe carries a PUCCH or a PUSCH for an N-UE. The N-subframe iscapable of carrying the L-PUSCH, but not the L-PUCCH, without overlapwith the PUCCH or the PUSCH for the N-UE in the frequency domain.

In FIG. 9, the system bandwidth is 5 MHz and includes 25 PRBs, i.e., PRB#0 to PRB #24. The N-UE is a wideband UE (i.e., a first type UE)supporting a bandwidth of 5 MHz, which is identical to the systembandwidth, and the L-UE is a narrow band UE (i.e., a second type UE)supporting a bandwidth of 1.4 MHz, which is narrower than the systembandwidth.

The eNB is capable of dividing the system bandwidth to generate one ormore sub-bands for an L-UE in an associated L-subframe.

In FIG. 9, the system bandwidth is divided into three subbands, i.e.,sub-band #1 902, sub-band #2 904, and sub-band #3 906. The bandwidth ofeach sub-band is 1.4 MHz, which the UE supports, and includes 6 PRBs.The L-UE operates on one of sub-band #1 902, sub-band #2 904, andsub-band #3 906 at a certain instance. The subbands are spaced apart byas much as a predetermined distance to avoid interfering with eachother. The sub-band #1 902 is spaced apart from an edge of the systemband by as much as f_(dl,offset,edge) 910, and is spaced apart from thesub-band #2 904 by as much as f _(dl,offset,Inter) 912. The sub-band #3906 is spaced apart from the other edge of the system band by as much asf_(dl,offset,edge) 916, and is spaced apart from the sub-band #2 904 byas much as f_(dl,offset,Inter) 914. The offsets, i.e.,f_(dl,offset,edge) 910, f_(dl,offset,Inter) 912, f_(dl,offset,Inter)914, and f_(dl,offset,edge) 916, and the bandwidth of each sub-band aresignaled from the eNB to the UE or set to hardcoded values agreedbetween the eNB and the UE.

In FIG. 9, reference numbers 922 and 924 denote frequency regionslocated at both edges of the system bandwidth for a PUCCH for an N-UE.In the N-subframe, the PUSCH and L-PUSCH can be multiplexed in thefrequency region with the exception of the regions 922 and 924. In thiscase, the resource available to be allocated for L-PUSCH transmission isrestricted to the sub-band predetermined for use of L-UE.

In the associated L-subframe, reference numbers 926 and 928 denote thePRBs at both edges of the sub-band #1 902 that are configured forL-PUCCH transmission of the L-UE.

In FIG. 9, reference number 926 or 828 corresponds to one PRB. Likewise,reference numbers 930 and 932 denote the PRBs at both edges of thesub-band #2 904 that are configured for L-PUCCH transmission of theL-UE. Also, reference numbers 934 and 936 denote the PRBs at both edgesof the sub-band #3 906 that are configured for L-PUCCH transmission ofthe L-UE.

In the associated L-subframe, the PUCCH transmission resources 922 and924 of the N-UE have f_(ul,offset,edge) 910 and f_(ul,offset,edge) 916wide enough to avoid overlapping with the L-PUCCH transmission resources926 and 936 of the L-UE. The f_(ul,offset,edge) 910 andf_(ul,offset,edge) 916 can be defined as a distance between the uplinksub-band for the L-UE and the PUCCH resource region for the N-UE. TheL-PUSCH transmitted by the L-UE in the associated L-subframe isrestricted to the frequency region excluding the L-PUCCH transmissionresource in the sub-band #1 902, sub-band #2 904, and sub-band #3 906.

In the LTE system, the UE transmits an SRS for the eNB to estimateuplink channel condition. The SRS is mapped to the last symbol of apredetermined uplink subframe and transmitted to the eNB on apredetermined frequency band. Likewise, an L-SRS as the SRS transmittedby L-UE is mapped to the last symbol of a predetermined uplink subframeand transmitted to the eNB on a predetermined frequency band accordingto an embodiment of the present invention.

FIG. 10 illustrates a sub-band configured for transmitting an L-SRS ofan L-UE in an LTE system according to an embodiment of the presentinvention. Specifically, FIG. 10 illustrates a certain sub-band 1010configured for use by the L-UE in an associated L-subframe 1000.

Referring to FIG. 10, the sub-band has a bandwidth of 1.4 MHz andincludes 6 PRBs. Reference numbers 1020 and 1030 denote the PRBs at bothedges of the sub-band 1010 as the frequency resource designated forL-PUCCH transmission of the L-UE. When the associated L-subframe isconfigured for an L-SRS transmission, the L-UE multiplexes L-SRS in thelast symbol 1040 of the associated L-subframe and transmits the L-SRS ona predetermined frequency band the sub-band for L-UE. When the L-PUCCHor L-PUSCH is transmitted with the L-SRS in the associated L-subframe,the L-UE punctures the last symbol of L-PUCCH or L-PUSCH and multiplexesthe L-PUCCH or L-PUSCH with the L-SRS.

The L-UE acquires the control information about the L-subframe andfrequency band for L-SRS transmission from the L-SIB. The L-SIB may alsoincluded the control information about the subframe and frequency bandfor SRS transmission of the N-UE. If the L-UE is scheduled by the eNB totransmit L-PUSCH in an N-subframe and if the N-subframe is configuredfor SRS transmission of the N-UE, the L-UE punctures the last symbol ofthe L-PUSCH to multiplex the L-PUSCH and SRS in the N-subframe.

FIG. 11 illustrates a sub-band configured for use by an L-UE in anassociated L-subframe in an LTE system according to an embodiment of thepresent invention.

Referring to FIG. 11, the sub-band for L-UE has a bandwidth of 1.4 MHzand includes 6 PRBs. Reference numbers 1120 and 1130 denote the PRBs atboth edges of the sub-band 1110 as the frequency resource designated forL-PUCCH transmission of the L-UE. The bandwidth of the RACH preamble1140, which is transmitted the L-UE to trigger a random accessprocedure, cannot be wider than the sub-band 1110 on which the L-UEoperates. Accordingly, the bandwidth of the RACH preamble is less thanthat corresponding to “bandwidth of sub-band for L-UE-number of PRBsallocated for L-PUCCH in sub-band for L-UE.” Because the sub-band for anL-UE is relatively narrow, the smallest unit of frequency bandwidth ofthe RACH preamble is 1 PRB, and the bandwidth of the RACH preamble canbe adjusted in units of 1 PRB. The RACH-related configurationinformation, such as bandwidth and position of RACH preamble, sub-band,and subframe available for RACH preamble transmission, is transmittedfrom the eNB to the L-UE through an L-SIB.

FIG. 12 is a block diagram illustrating an eNB according to anembodiment of the present invention.

Referring to FIG. 12, the eNB includes a controller 1208, an encoder1210, a modulation mapper 1212, an RE mapper 1214, an OFDM signalgenerator 1216, and antenna 1218, and an information formatter 1220.

The controller 1208 configures an L-subframe/N-subframe and a sub-bandfor an L-UE by referencing the numbers of L-UEs and N-UEs to besupported in the system and a resource amount available in the systemand each sub-band. The controller 1208 controls the informationformatter 1220 to generate control information or data to the L-UE. Thecontroller 1208 controls the encoder 1210, the modulator 1212, and theRE mapper 1214 according to the channel coding scheme, modulationscheme, and time-frequency resource mapping scheme determined for thephysical channel to be transmitted.

The information formatter 1220 includes an MIB generator 1200, an L-MIBgenerator 1202, a Downlink Control Information (DCI) generator 1204, anda data generator 1206.

The MIB generator 1200 formats the MIB including information on the DLsystem bandwidth, a PHICH resource, and an SFN, which are used by the UEto access the system, in the PBCH transmission format.

The L-MIB generator 1202 generates an L-MIB including the controlinformation related to the configuration of L-subframe and sub-band forL-UE. The L-MIB may include at least one of a subframe configurationindex, L-PHICH resource information, DL sub-band bandwidth configurationinformation, and a search space. The L-MIB generator 1202 formats thecontrol information in the PBCH transmission format. The formatted MIBand L-MIB are multiplexed into the PBCH, encoded by the encoder 1210according to the channel coding scheme defined for PBCH, modulated bythe modulator 1212, and mapped to time-frequency resource by the REmapper 1214. The PBCH mapped to the time-frequency resource is processedby the OFDM signal generator 1216 and then transmitted to the UE throughthe antenna 1218.

The DCI generator 1204 generates DCI for an N-UE or an L-UE in a PDCCHor an L-PDCCH transmission format. The formatted DCI is encoded by theencoder 1210 according to the channel coding scheme defined for thePDCCH or the L-PDCCH, modulated by the modulator 1212, and mapped to thetime-frequency resource carrying the PDCCH or the L-PDCCH by the REmapper 1214. The DCI is processed by the OFDM signal generator 1216 andthen transmitted to the UE through then antenna 1218.

The data generator 1206 generates the data addressed to the N-UE or theL-UE in the PDSCH or the L-PDCCH transmission format. The data addressedto the L-UE includes an L-SIB. The formatted data is encoded accordingto the channel coding scheme defined for the PDSCH or the L-PDSCH by theencoder 1210, modulated by the modulator 1212, and mapped to thetime-frequency resource for transmitting PDSCH or L-PDSCH by the REmapper 1214. The data are processed by the OFDM signal generator 1216and then transmitted to the UE through the antenna 1218.

FIG. 13 is a block diagram illustrating an L-UE according to anembodiment of the present invention.

Referring to FIG. 13, the L-UE includes an L-PUSCH generator 1300, anL-PUCCH generator 1302, a RACH preamble generator 1304, an L-SRSgenerator 1306, a controller 1308, an encoder 1310, a modulator 1312, atransform precoder 1314, an RE mapper 1316, an SC-FDMA signal generator1318, and an antenna 1320.

The controller 1308 of the L-UE controls transmission of uplink signalssuch as an L-PUSCH, an L-PUCCH, a RACH preamble, and an L-SRS based oncontrol information such as an MIB, an L-MIB, and an L-SIB received fromthe eNB. The controller 1308 controls the encoder 1310, the modulator1312, and the RE mapper 1316 according to the channel coding scheme,modulation scheme, and time-frequency resource mapping scheme definedfor physical channels to be transmitted.

If uplink scheduling information is received from the eNB, the L-PUSCHgenerator 1300 generates an L-PUSCH corresponding to the uplinkscheduling information and the encoder 1310 encodes the L-PUSCHaccording to a channel coding scheme defined for the L-PUSCH. Themodulator 1312 modulates the coded signal, the transform precoder 1314DFT-processes the modulated signal, and the RE mapper 1316 maps theprocess result to the time-frequency resource allocated for the L-PUSCH.The SC-FDMA signal generator 1318 processes the data, which is thentransmitted to the eNB through the antenna 1320.

In order to transmit an uplink HARQ ACK/NACK or an L-CQI, the L-PUCCHgenerator 1302 configures the L-PUCCH, the encoder 1310 encodes theL-PUCCH according to the channel coding scheme defined for L-PUCCH, themodulator 1312 modulates the encoded signal, and the RE mapper 1316 mapsthe modulated signal to the time-frequency resource allocated forL-PUCCH transmission. The L-PUCCH is processed by the SC-FDMA signalgenerator 1318 and then transmitted to the eNB through the antenna 1320.

In order to perform random access, the RACH preamble generator 1304configures a RACH preambleand the RE mapper 1316 maps the RACH preambleto the time-frequency resource allocated for RACH preamble transmission.The RACH preamble is processed by the SC-FDMA signal generator 1318 andthen transmitted to the eNB through the antenna 1320.

In order to transmit an L-SRS, the L-SRS generator 1306 generates theL-SRS and the RE mapper 1316 maps the L-SRS to the time-frequencyresource allocated for L-SRS transmission. The L-SRS is processed by theSC-FDMA signal generator 1318 and then transmitted to the eNB throughthe antenna 1320.

As described above, the system access method of a narrowband UEaccording to the present invention is advantageous in that thenarrowband UEs can be supported along wideband UEs in a wirelesscommunication system.

Although certain embodiments of the present invention have beendescribed in detail hereinabove, it should be clearly understood thatmany variations and/or modifications of the basic inventive conceptsherein taught which may appear to those skilled in the present art willstill fall within the spirit and scope of the present invention, asdefined in the appended claims and their equivalents.

What is claimed is:
 1. A base station in a wireless communication systemsupporting first type terminals operating on a first bandwidth andsecond type terminals operating on a second bandwidth, the base stationcomprising: a transceiver configured to: transmit a master informationblock (MIB) and a system information block (SIB), wherein the MIBincludes control information on an subframe configuration for supportinga second type terminal and a sub-band configuration of the subframe, andwherein the SIB includes information on downlink reception and uplinktransmission of the second type terminal, and receive a Random AccessChannel (RACH) preamble request from one of the first type terminals andthe second type terminals; and a controller configured to: control thetransceiver to transmit MIB and SIB and to receive the RACH preamblerequest from one of the first type terminals and the second typeterminals, and perform a random access procedure, when a RACH preamblerequest is received from one of the first type terminals and the secondtype terminals, wherein the second bandwidth is narrower than the firstbandwidth.
 2. The base station of claim 1, wherein the transceiver isfurther configured to broadcast the MIB on a physical broadcast channel(PBCH), and wherein the MIB includes at least one of a subframeconfiguration index, physical hybrid automatic repeat request indicatorchannel (PHICH) resource information, downlink sub-band bandwidthconfiguration information, and a search space.
 3. The base station ofclaim 1, wherein the transceiver is further configured to transmit theSIB on a physical downlink shared channel (PDSCH) carrying dataaddressed to the second type terminal, and wherein the SIB includes atleast one of a downlink sub-band position, uplink sub-band bandwidthconfiguration information, uplink sub-band bandwidth configurationinformation, an uplink sub-band position, physical random access channel(PRACH) configuration information, and physical channel configurationinformation.
 4. The base station of claim 1, wherein the L-subframecarries control information for a first type terminal in first N symbolsand control information for the second type terminal in symbols afterthe first N symbols.
 5. The base station of claim 1, wherein thetransceiver is further configured to receive a sounding reference signalat a last symbol of a predetermined uplink subframe transmitted by thesecond type terminal.
 6. A terminal in a wireless communication systemsupporting first type terminals operating on a first bandwidth andsecond type terminals operating on a second bandwidth, the terminalcomprising: a transceiver configured to receive a synchronizationchannel (SCH), a master information block (MIB), and a systeminformation block (SIB), and to transmit a random access channel (RACH)preamble to the base station based on the received MIB and the receivedSIB, wherein the received MIB includes control information on ansubframe configuration for supporting a second type terminal and asub-band configuration of the subframe, and wherein the SIB includesinformation on downlink reception and uplink transmission of the secondtype terminal; and a controller configured to control the transceiver toreceive the SCH, the MIB, and the SIB, and to transmit the RACH preambleto the base station based on the received MIB and the received SIB,wherein the second bandwidth is narrower than the first bandwidth. 7.The terminal of claim 6, wherein the transceiver is further configuredto receive the MIB on a physical broadcast channel (PBCH), and whereinthe MIB includes at least one of a subframe configuration index,physical hybrid automatic repeat request indicator channel (PHICH)resource information, downlink sub-band bandwidth configurationinformation, and a search space.
 8. The terminal of claim 6, wherein thetransceiver is further configured to receive the SIB on a physicaldownlink shared channel (PDSCH) carrying data addressed to the secondtype terminal, and wherein the SIB includes at least one of a downlinksub-band position, uplink sub-band bandwidth configuration information,uplink sub-band bandwidth configuration information, an uplink sub-bandposition, physical random access channel (PRACH) configurationinformation, and physical channel configuration information.
 9. Theterminal of claim 6, wherein the L-subframe carries control informationfor a first type terminal in first N symbols and control information forthe second type terminal in symbols after the first N symbols.
 10. Theterminal of claim 6, wherein the transceiver is further configured totransmit a sounding reference signal at a last symbol of a predetermineduplink subframe transmitted by the second type terminal.